The invention relates to an apparatus for changing printing cylinder sleeves in printing machines, including two bearing blocks which serve for the rotatable support of the printing cylinder sleeve during operation of the printing machine, a shaft running axially through the printing cylinder sleeve, and a lifter disposed at one end of the shaft, outside of the corresponding bearing block, by which the shaft together with the printing cylinder sleeve can be lifted and cantilevered, such that the printing cylinder sleeve comes free of the bearing blocks and can be withdrawn axially from the shaft.
Apparatus of this kind, which are used in printing machines with a so-called sleeve system, are known from practice. In this system the printing cylinder has a replaceable hollow cylindrical sleeve of plastic on whose external circumference the printing plates are placed. The inside diameter of the sleeve is matched to the outside diameter of the shaft so that the sleeve can be pushed onto the shaft. The outside diameter of the sleeve is determined by the desired length of the print. The printing machine can be set up for different print lengths by exchanging the sleeve.
The shaft is provided with both ends protruding from the sleeve, and has bearing sections which are mounted in the bearing blocks. The sleeve thus rests on the bearing blocks only indirectly through the shaft.
This design has the disadvantage that not only a precise mounting of the shaft in the bearing blocks, but also a precise seating of the sleeve on the shaft have to be assured if perfect print quality is to be achieved. Furthermore, the outside diameter of the bearing on the shaft must always be smaller than the inside diameter of the sleeve so that the sleeve can be pulled axially from the shaft. Therefore only a limited diameter range is available for mounting the shaft.
Another disadvantage is that the sleeves must have a relatively great wall thickness, so that the sleeves have a relatively great weight and the dimensional accuracy of production of the sleeves is made difficult.